Heat storage and control system for improving the convenience and efficiency of wood burning stoves

ABSTRACT

This claim is an improvement to existing and commercially available domestic heating systems which consist of an outdoor wood burning stove and boiler which recirculate hot water through radiators located inside an inhabited structure or domicile. The inventor proposes the efficiency and convenience of such ‘outdoor wood burning heating systems’ are substantially improved by the addition of a large storage tank for the heated water and an electronic control system. The claimed improvement allows the firebox to be stoked and ignited at a time convenient to the dwelling occupant. Heated water is stored in an insulated water tank until called upon for heating. Combustion is optimized for maximum efficiency and atmospheric emissions are substantially reduced.

BACKGROUND

The use of firewood as a fuel for domestic heating dates fromprehistory. In recent years, the increasing cost of fossil fuels hasmotivated many homeowners, particularly those living in rural areaswhere firewood is relatively inexpensive and plentiful, to return towood burning stoves as a primary source of heating their homes duringperiods of cold weather.

Burning firewood within the confines of an inhabited structure is aninherently dangerous activity. The high risk of errant hot embers,creosote accumulation in the chimney, or other mishaps can result in acatastrophic fire.

In an attempt to mitigate these hazards, a number of commercialinnovators have in recent years developed ‘outdoor wood burning stoves’.These outdoor systems place the entire combustion process within aseparate enclosure which is located at some safe distance away from theoccupied structure. An open boiler or similar arrangement is used toheat water and then transfer heat from the combustion of the firewood toan arrangement of heat exchangers or a radiator(s) located inside aninhabited structure, home, out buildings, and/or providing hot potablewater.

Currently available outdoor wood stove heating systems (hereafterreferred to as ‘outdoor wood stoves’) typically consist of certaincomponents shared with the claimed improvement, including a “thermostat”(Item 2), “firebox” (Item 10), “boiler” (Item 11), “boiler waterrecirculating pump” (Item 19), and “radiators” (Item 32).

Background, Continued

Current ‘outdoor wood stoves’ begin operation with the operator loadingand igniting fuel in a “firebox” (Item 10). The heat from saidcombustion causes water in the “boiler” (Item 11) to become heated. Hotwater from the “boiler” (Item 11) is circulated by a “boiler watercirculation pump” (Item 19). Heated water enters the home or otherinhabited structure and is circulated through one or more “radiators” orsimilar heat exchangers (Item 32) to impart heating to the homeinterior. The water is circulated so that it returns directly to the“boiler” (Item 11) where it is reheated.

Many commercially available ‘outdoor wood stoves’ attempt to control thequantity of heat provided by the system by monitoring the interiortemperature of the home with a “thermostat” (Item 2) and subsequentlyelectrically operating a combustion air flue to increase or decrease theamount of air available for combustion.

Commercially available ‘outdoor wood stoves’ as outlined in ‘paragraphs003 through 006’ remove undesirable odor, ashes, and housekeepingproblems associated with traditional interior fireplaces, fireplaceinserts, or other wood burning heating appliances.

Commercially available ‘outdoor wood stoves’ as outlined in ‘paragraphs003 through 006’ also offer the advantage of consuming low qualityfirewood which may be undesirable for use in interior wood burningstoves, fireplaces, or appliances.

Background, Continued

While removing the combustion activity from the occupied structure hasmade currently available outdoor wood burning heating systems safer anddesirable to more users, there remain several inherent shortcomings inthese systems such as failing to provide a method of storing asignificant quantity of heat energy.

Commercially available wood stove heating systems such as those outlinedin ‘paragraphs 003 through 006’ have the disadvantage of requiring theoperator, homeowner, or tenant to stoke the firebox and/or reignite afire whenever the current supply of fuel is consumed in the firebox andmore heating is desired within the habitation. This often requires theoperator to stoke and/or relight the stove several times a day if thehome interior is to be maintained at a comfortable or consistenttemperature. By contrast, a homeowner or tenant using the Inventor'scontrol and heat storage system could stoke and ignite the fireboxduring convenient daylight hours rather than awaken during the wee, darkhours of the night to reload or reignite fuel in the firebox.

Current ‘outdoor wood stoves’ require an inconvenient and unacceptablylong period of time from when the firebox is stoked and/or reignited tothe time the interior of the domicile receives the resulting warmth fromrenewed combustion.

Background

The inlet flue of most current ‘outdoor wood stoves’ is controlleddirectly by a thermostat to control the air supply to and resultingintensity of combustion in the firebox. This control strategy isincapable of consistently optimizing combustion efficiency. The attemptby existing systems to extend burn time by restricting air flow to thefirebox results in anaerobic ‘roasting’ of the wood and increased smokeand emissions. As a result, ‘outdoor wood stoves’ emit unacceptably highlevels of incompletely combusted hydrocarbons, produce an offensivevolume of smoke, and consume an excessive quantity of fuel.

The current design of ‘outdoor wood stoves’ does not incorporatesophisticated, multipoint collection of water temperature or combustiondata. This lack of critical process information precludes ‘closed loop’control of the combustion process. Increasing the quantity and qualityof data collection inputs to a microprocessor provides an opportunityfor various alarms and controls which will improve the efficiency,convenience, reliability and safety of the heating system.

DESCRIPTION OF DRAWINGS

Drawing One—A schematic representation of an outdoor wood burning stoveheating system with the addition of the Inventor's claimed improvedcontrols and heat storage system.

EXPLANATION OF SCHEMATIC DRAWING

Item 1 is a microprocessor-based electronic “system control module”. Thesystem control module receives input signals from various temperaturesensors, operator inputs, and thermostat signals. Proprietaryprogramming of the “system control module” interprets these inputs tocause desired operation of the improved heating system and achieve theclaimed improvements in efficiency and convenience. When a potentiallydangerous condition occurs, the controller provides alarm output to thesystem operator and interrupts the supply of combustion air to the“firebox” (Item 10) by interrupting the control signal to the “remoteactuated flue damper” (Item 28).

Item 2 is a commercially available “thermostat” as typically used tocontrol forced air, radiant, and most domestic heating systems.

Item 3 is a commercially available “safety relief valve” as typicallyinstalled on hot water heaters, boilers, and many existing outdoor woodstove systems. The “safety relief valve” opens in the event ofoverheating or over-pressurization of the “boiler” (Item 11).

Item 4 is a commercially available liquid temperature sensor which isused in the claimed invention as a “boiler temperature sensor”. Thesignal from the “boiler temperature sensor” is an input to the “systemcontrol module” (Item 1) for various system optimization functionsincluding an over-temperature warning. The “boiler temperature sensor”input is wired as a fail-safe signal so that a ‘no signal condition’ isprogrammed as an over-temperature condition.

Explanation of Schematic Drawing, Continued

Item 5 is a commercially available oxygen sensor such as that used tomonitor modern, emission compliant automotive engine exhaust streams.This sensor is incorporated in the claimed invention as the “combustionoxygen sensor” to provide an input to the “system control module” (Item1).

Item 6 is a commercially available liquid pressure switch which is usedin the claimed invention as a “boiler return pressure sensor”. Thesignal from the “boiler return pressure sensor” is an input to the“system control module” (Item 1) to confirm water is entering the“boiler” (Item 11). This input is wired as a fail-safe signal so that a‘no signal condition’ is programmed as a ‘loss of water to boiler’condition.

Item 7 is a commercially available liquid temperature sensor which isused in the claimed invention as a “heat reservoir temperature sensor”.The signal from the “heat reservoir temperature sensor” is an input tothe “system control module” (Item 1). A low temperature signal from the“heat reservoir temperature sensor” causes the “system control module”(Item 1) to provide an informational alarm and inform the operator thatthe “firebox” (Item 10) needs to be stoked and ignited.

Explanation of Schematic Drawing, Continued

Item 8 is a commercially available high-temperature sensor which is usedin the claimed invention as a “combustion exhaust temperature sensor”.The signal from the “combustion exhaust temperature sensor” is an inputto the “system control module” (Item 1). The “system control module”(Item 1) examines this input and adjusts the supply of combustion airvia the “remote actuated flue damper” (Item 28) to optimize combustionin the “firebox” (Item 10) and minimize atmospheric emissions from the“chimney” (Item 29).

Item 9 is a commercially available fluid level switch which is used inthe claimed invention as the “heat reservoir level switch”. Aninsufficient water level in the “heat reservoir tank” (Item 22)interrupts the signal from the “heat reservoir level switch”, andresults in an alarm condition output from the “system control module”(Item 1).

Item 10 is a schematic representation of the “firebox” of an ‘outdoorwood stove’. Firewood or similar combustible materials are burned withinthe confines of this “firebox”. No improvement of the “firebox” isclaimed but is depicted for reference purposes.

Item 11 is a schematic representation of the boiler of a typical‘outdoor wood stove’. Water heated within this “boiler” is used totransfer heat to the “domestic structure” (Item 31). No improvement tothe “boiler” is claimed but is depicted for reference purposes.

Explanation of Schematic Drawing, Continued

Item 12 is a commercially available three-way valve which serves as a“fast-heat bypass valve”. The “fast-heat bypass valve” determines thedestination for heated water exiting from the “boiler” (Item 11) via the“boiler supply line” (Item 14). The heated water may be directed forstorage in the “heat reservoir tank (item 22) via the “reservoir returnline” (Item 15), or to the “radiators” (Item 32) via the “radiatorsupply line” (Item 16). Operation of the “fast-heat bypass valve” iscontrolled by the “system control module” (Item 1).

Item 13 is the “boiler return line”, a pipe enabling the return flow ofcool water from the “heat reservoir tank” (Item 22) to the “boiler”(Item 11). The “boiler return line” is a component of currentcommercially available ‘outdoor wood stoves’ which is modified orrerouted in course of retrofitting this invention to an existing‘outdoor wood stove’.

Item 14 is the “boiler supply line”, a pipe providing the flow of hotwater from the “boiler” (Item 11) to “fast-heat bypass valve” (Item 12).The “boiler supply line” is a component of current commerciallyavailable ‘outdoor wood stoves’ which is modified or rerouted in courseof implementing this invention to an existing ‘outdoor wood stove’.

Item 15 is the “reservoir return line”, a pipe providing the flow of hotwater from the “boiler supply line” (Item 14) through the “fast-heatbypass valve” (Item 12) to replenish the “heat reservoir tank” (Item22).

Explanation of Schematic Drawing, Continued

Item 16 is the “radiator supply line”, a pipe providing the flow of hotwater to the “radiators” (Item 32) from either the “boiler supply line”(Item 14) or the “heat reservoir supply line” (Item 18), depending onthe position of the “fast-heat bypass valve” (Item 12).

Item 17 is the “radiator return line”, a pipe which returns cool waterexiting the “radiators” (Item 32) and discharges into the “heatreservoir tank” (Item 22).

Item 18 is the “reservoir supply line”, a pipe providing the flow ofstored hot water from the “heat reservoir tank” (Item 22) to the“radiators” (Item 32) via the “radiator supply line” (Item 16).

Item 19 is a commercially available motor driven centrifugal water pumpsimilar to that typically supplied as part of currently available‘outdoor wood stoves’ as a “boiler water circulation pump”. The “boilerwater circulation pump” is used to circulate heated water through theheating system. The inlet source of the “boiler water circulation pump”is modified in the course of implementing this invention to an existing‘outdoor wood stove’ to draw water from the “heat reservoir tank” (Item22). Operation of the “boiler water circulation pump” is controlled bythe “system control module” (Item 1).

Explanation of Schematic Drawing, Continued

Item 20 is a commercially available centrifugal water pump incorporatedinto the invention as the “reservoir water circulation pump”. The“reservoir water circulation pump” moves warm water from the “heatreservoir tank” Item 22), through the “radiator supply line” (Item 16),radiators (Item 32), and “radiator return line” (Item 17). Operation ofthe “reservoir water circulation pump” is controlled by the “systemcontrol module” (Item 1). The functions of the “reservoir watercirculation pump” and “boiler water circulation pump” (Item 19) could beperformed with a single pump with certain changes to the system'splumbing but are depicted as two separate pumps in the interest ofsimplicity in this claim.

Item 21 is “tank insulation” which is applied to the exterior of the“heat reservoir tank” (Item 22) to extend the period of time heat isretained within the “heat reservoir tank” (Item 22) and improve thethermal efficiency of the system. This insulation may be fabricated froma variety of materials, including but not limited to common commerciallyavailable fiberglass wool or expanded polystyrene.

Item 22 is a commercially available large capacity water tank, typicallywith a capacity of 500 to 2,000 gallons. The “heat reservoir tank”provides storage of heated water for a period of up to several daysuntil such time as heating of the “domestic structure” (Item 31) isrequired.

Item 23 is a commercially available fluid check valve incorporated intothe invention as the “fast-heat check valve”. This check valve preventswater from back flowing from the “reservoir supply line” (Item 18) intothe “boiler supply line” (Item 14).

Explanation of Schematic Drawing, Continued

Item 24 is a commercially available fluid check valve incorporated intothe invention as the “reservoir check valve”. This check valve preventswater from back flowing from the “boiler supply line” (Item 14) into the“reservoir supply line” (Item 18).

Item 25 is a commercially available fluid check valve incorporated intothe invention as the “boiler return check valve”. This check valve isimportant to the safe operation of the system as it insures water cannotbackflow out of the “boiler” (Item 11) via the “boiler return line”(Item 13).

Item 26 is a commercially available vacuum relief valve incorporatedinto the invention as the “vacuum relief valve”. This relief valve isimportant to the safe operation of the system as it vents air which maybecome entrapped in the water entering the “boiler” (Item 11) via the“boiler return line” (Item 13).

Item 27 is a commercially available pressure reducing water valve usedin the claimed invention as a “make-up water supply valve” to replenishwater consumed or lost in the heating system.

Item 28 is a “remote actuated flue damper” which controls the flow ofair into the combustion area or “firebox” (Item 10). Controlling theamount of air available for combustion allows the rate and temperatureof combustion to be optimized for peak efficiency, improved safety,and/or reduced atmospheric emissions. Automatic and/or electricalactuation of the “remote actuated flue damper” is controlled by the“system control module” (Item 1). In the event that the control signalis interrupted, the flue assumes a closed or ‘fail-safe’ condition.

Explanation of Schematic Drawing, Continued

Item 29 is the “chimney” through which smoke and combustion byproductsexit the “firebox” (Item 10). No improvement to the “chimney” is claimedbut is depicted for contextual purposes.

Item 30 is the “firebox enclosure” which contains the “firebox” (Item10) and generally provides in situ structural support of the “boiler”(Item 11). The “firebox enclosure” may be constructed from steel,firebrick, or similar materials. No improvement is claimed for the“firebox enclosure” but is depicted for contextual purposes.

Item 31 is the “domestic structure”, a domicile, building, or otherentity to be heated by the system. No improvement is claimed for the“domestic structure” but is depicted for contextual purposes.

Item 32 is a liquid-to-air heat exchanger consisting of one or more“radiators” through which heated water is pumped to impart convectionheating of the interior of a “domestic structure” (Item 31). The“radiators” may be part of the home's original hot-water heating systemor component(s) added in the course of installing a commerciallyavailable ‘outdoor wood stove’ heating system. No improvement to the“radiators” are claimed but are depicted for contextual purposes.

Explanation of Schematic Drawing, Continued

Item 33 is a “pressurized water source” such as municipal water utilityor well water system. The “pressurized water source” is not part of thisclaim but is depicted for contextual purposes.

Item 34 is the “make-up water supply line”, a pipe providing cool waterfrom the “make-up water supply valve” (Item 27) to the “boiler returnline” (Item 13) to replenish water as it is consumed or lost in theclaimed heating system.

Description of the Claim and Invention

001) Initiating the heating process—The dwelling occupant or operatorplaces firewood or a similar fuel into the “firebox” (Item 10″) of theclaimed ‘improved outdoor wood stove heating system’. The operatorignites the firewood with the resulting heat of combustion causing thewater residing in the “boiler” (Item 11) to be heated.

002) Combustion verification—The rising temperature of exhaust gases inthe “chimney” (Item 29) causes a signal to be produced by the“combustion exhaust temperature sensor” (Item 8) and produces an inputto the “system control module” (Item 1). The rising temperature of thewater in the “boiler” (Item 11) produces a signal from the “boilertemperature sensor” (Item 4). These signals and/or other operator inputsinto the “system control module” (Item 1) cause the “boiler watercirculation pump” (Item 19) to begin operation.

003) Boiler circulation—Water is withdrawn from the “heat reservoirtank” (Item 22) via the “boiler return line” (Item 13) by the “boilerwater circulation pump” (Item 19). The circulation of water imparted bythe “boiler water circulation pump” (Item 19) moves water through the“boiler” (Item 11), through the “boiler supply line” (Item 14) andtoward the “fast-heat bypass valve” (Item 12).

Description of the Claim and Invention, Continued

004) Cold home start-up—In the event that the “thermostat” (Item 2)setting is calling for heat, i.e. the interior of the “domesticstructure” (Item 31) is cold, the “system control module” (Item 1) willposition the “fast-heat bypass valve” (Item 12) to direct water heatedin the manner described in ‘paragraph 003’ to flow into the “radiatorsupply line” (Item 16). Heated water circulates through the “radiators”(Item 32) and imparts heating to the interior of the “domesticstructure” (Item 31). Cool water exits the “radiators” (Item 32) via the“radiator return line” (Item 17) and is discharged into the “heatreservoir tank” (Item 22).

005) Home set-point achieved—Water circulates through the system asdescribed in ‘paragraphs 002 through 004’ until such time as the setpoint of the “thermostat” (Item 2) is achieved and results in an inputto the “system control module” (Item 1).

006) Begin surplus heat storage—In the event combustion is stilloccurring in the “firebox” (Item 10) and water continues to be heated inthe “boiler” (Item 11) as described in ‘paragraph 002’, and the“thermostat” (Item 2) set point is achieved as described in ‘paragraph005’, the “system control module” (Item 1) will cause the “fast-heatbypass valve” (Item 12) to direct hot water into the “heat reservoirtank” (Item 22) via the “reservoir return line” (Item 15) and beginstoring heated water in the “heat reservoir tank” (Item 22) for futureuse.

Description of the Claim and Invention, Continued

007) Heat storage capacity achieved—The temperature of water containedwithin the “heat reservoir tank” (Item 22) is continuously monitored bythe “heat reservoir temperature sensor” (Item 7) and is an input to the“system control module” (Item 1). In the event combustion continues andthe temperature of the water in the “heat reservoir tank” (Item 22)rises above a predetermined level e.g. 170 degrees Fahrenheit, aninformational alarm is produced by the “system control module” (Item 1)to alert the operator that no further stoking of the “firebox” (Item 10)is necessary.

008) Heat storage capacity surpassed—The temperature of water containedwithin the “heat reservoir tank” (Item 22) is continuously monitored bythe “heat reservoir temperature sensor” (Item 7) and is an input intothe “system control module” (Item 1). In the event combustion continuesand the temperature of the water in the “heat reservoir tank” (Item 22)rises above a predetermined level e.g. 190 degrees Fahrenheit, the“system control module” (Item 1) interrupts the control signal to the“remote actuated flue damper” (Item 28) and terminates the flow ofcombustion air to the “firebox” (Item 10) to prevent overheating of thesystem.

Description of the Claim and Invention, Continued

009) ‘Call’ for post combustion heating of the home—At such time as theavailable fuel in the firebox is consumed and depleted, the temperatureof water in the “boiler” (Item 11) will fall to a temperature equal toor lower than the temperature of water stored inside the “heat reservoirtank” (Item 22). Under these condition, when the “thermostat” (Item 2)calls for heat, the “system control module” (Item 1) will direct the“reservoir water circulation pump” (Item 20) to operate. Warm water fromwithin the “heat reservoir tank” (Item 22) is drawn by the “reservoirwater circulation pump” (Item 20) through the “heat reservoir supplyline” (Item 18) through the “heat reservoir check valve” (Item 24) andinto the “radiators” (Item 32) located within the “domestic structure”

-   -   (Item 31). Water exits the “radiators” (Item 32), travels        through the “radiator return line” (Item 17) and discharges into        the “heat reservoir tank” (Item 22).

010) Post combustion heating of the home ‘achieved’ Water continues tocirculate as described in ‘paragraph 009’ until such time as the setpoint of the “thermostat” (Item 2) is achieved. Operation of the“reservoir water circulation pump” (Item 20) is then interrupted by the“system controller module” (Item 1) until a demand for heating of the“domestic structure” (Item 31) is again called for by the “thermostat”(Item 2).

011) Transfer of heat from reservoir to home—Circulation as described in‘paragraphs 009 and 010’ continues even when combustion in the “firebox”is limited or nonexistent. The temperature of the water contained by the‘heat reservoir tank’ (Item 22) will drop as circulation through the“radiators” (Item 32) causes heat to be transferred by convectionheating of the “domestic structure” (Item 31) and other losses.

Description of the Claim and Invention, Continued

012) Call for firebox replenishment—At some point the temperature of thewater inside the “heat reservoir tank” (Item 22) will drop to a pointwhere it can only provide a few additional hours of heating to the“domestic structure” (Item 31). An input signal at approximately 110degrees Fahrenheit from the “heat reservoir temperature sensor” (Item 7)to the “system control module” (Item 1) will cause an informationalalarm alerting the operator that the “firebox” (Item 10) should bereplenished and ignited.

013) Replenishment of boiler water—Safe operation of all boiler systemsrequire that an adequate quantity of water is always present in theboiler. A reliable supply of pressurized water is connected to theclaimed system as the “pressurized water source” (Item 34). The“pressurized water source” (Item 34) is connected to a “make-up watersupply valve” (Item 27) which in turn provides a reliable supply ofwater to the “boiler” (Item 11) via the “boiler return line” (Item 13).The pressure setting of the “make-up water supply valve” (Item 27) isadjusted to equal the head pressure of the system as required tomaintain proper water level in heat reservoir tank or alternatively thehighest point in the system.

014) Active water level monitoring—In certain applications, the waterlevel in the “heat reservoir tank” (Item 22) will be higher than theelevation of the “boiler” (Item 11). The “heat reservoir level switch”(Item 9) monitors the water level inside the “heat reservoir tank” (Item22) and provides a signal to the “system control module” (Item 1). Thesystem control module produces an alarm condition if the water levelinside the “heat reservoir tank (Item 22) is inadequate or couldjeopardize the quantity of water available to “boiler” (Item 11).

Description of the Claim and Invention, Continued

015) Redundant protection provided by safety relief valve—In the eventthe temperature and/or pressure inside the “boiler” (Item 11) reaches apotentially dangerous level, the “safety relief valve” (Item 3) willopen and allow hot water and steam to escape into the atmosphere.Operation of the “safety relief valve” (Item 3) is completelyindependent of the “system control module” (Item 1) or any other systemcomponent.

016) In practice, the amount of heat energy generated by the combustionof 40 to 100 pounds of firewood (a typical firebox stoking) exceeds theamount of heat required to return a typical 1,500 to 3,000 square foothome to a comfortable interior temperature. Therefore, combustion in the“firebox” (Item 10) can be expected to continue after achieving the setpoint of the “thermostat” (Item 2). In the claimed system, heated watercontinues to flow from the “boiler” (Item 11) through the “fast heatbypass valve” (Item 12) and discharges into the “heat reservoir tank”(Item 22) thus causing the water therein to increase in temperature. The“heat reservoir tank” (Item 22) is surrounded by “tank insulation” (Item21) allowing the heated water within the tank to remain at an elevatedtemperature for an extended period of time, thus achieving theInventor's ‘claim I’ to “Provide a means of storing a substantialquantity of heat energy for a period of up to several days after saidheat is produced by the stove's combustion process.”

017) The ability of the claimed system to automatically provide heat tothe domicile as described in ‘paragraphs 009, 010, and 011’ even whenthe firebox and boiler are inactive achieves the inventor's ‘claim II’to “Provide a means of operating the stove in a manner more convenientfor the homeowner's or tenant's lifestyle by allowing fuel loading(stoking) of the firebox and/or initiation of the combustion process(lighting) at a time convenient to the tenant or homeowner rather thanat the time heat is required.”

Description of the Claim and Invention, Continued

018) The claimed system utilizes a ‘closed loop’ strategy tocontinuously monitor inputs such as those from the “combustiontemperature sensor” (Item 8) and/or the “combustion oxygen sensor” (Item5). The “system control module” (Item 1) examines these inputs and isprogrammed to automatically make appropriate adjustments to the positionof the “remote actuated flue damper” (Item 28) to control the amount ofair entering the “firebox” (Item 10) to optimize combustion efficiencyand safety. The ability of the system to monitor and continuously makeadjustments to the combustion process achieves the Inventor's claim IIIto “Provide an improved method of monitoring and controlling thecombustion in the stove firebox, and thus provide the simultaneousbenefits of reduced airborne emissions and reduced fuel consumption.”

019) The “system control module” (Item 1) is mounted in a convenientlocation within the “domestic structure” (Item 31). The tenant,homeowner or operator may readily determine the operating condition ofthe claimed improved outdoor wood burning stove heating system withoutleaving the comfort of the home interior, thus achieving the Inventors‘claim IV’ to “Provide an improved means of monitoring stove operationfrom a remote location such as from within the interior of the home andthus increase the ease and convenience of operating a wood burningheating system.

Description of the Claim and Invention, Continued

020) If the temperature detected by either the “heat reservoirtemperature sensor” (Item 7) or the “boiler temperature sensor” (Item 4)exceed certain preset value, the “system control module” (Item 1) willenter an alarm mode and direct the “remote actuated flue damper” (Item28) to close and substantially reduce the rate of combustion. Theability of the “system control module” to interpret various inputs andproduce alarm condition outputs provides a level of equipment protectionand safety not found in current generation ‘outdoor wood stoves’, thusachieving the Inventors ‘claim V’ to “Provide more reliable andsophisticated methods of monitoring and controlling the combustionprocess and boiler operation and thus reduce the risks of personalinjury and/or property damage associated with current generation‘outdoor wood stoves’ which are relatively unsophisticated'.

I. Provide a means of storing a substantial quantity of heat energy fora period of up to several days after said heat is produced by thestove's combustion process. II. Provide a means of operating the stovein a manner more convenient for the homeowner's or tenant's lifestyle byallowing fuel loading (stoking) of the firebox and/or initiation of thecombustion process (lighting) at a time convenient to the tenant orhomeowner rather than at the time heat is required. III. Provide animproved method of monitoring and controlling the combustion in thestove firebox, and thus provide the simultaneous benefits of reducedairborne emissions and reduced fuel consumption. IV. Provide an improvedmeans of monitoring stove operation from a remote location such as fromwithin the interior of the home and thus increase the ease andconvenience of operating a wood burning heating system. V. Provide morereliable and sophisticated methods of monitoring and controlling thecombustion process and boiler operation and thus reduce the risks ofpersonal injury and/or property damage associated with currentgeneration, ‘outdoor wood stoves’ which are relatively unsophisticated.